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3 years ago

15 POINTS! DUE SOON! Write the series using summation notation. 7 + 10 + 13 + 16 + 19

Mathematics

1 answer:

Colt1911 [192]3 years ago

4 0

Answer to your question is 52

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HELP ON THIS PROBLEM!! Solve the following 0deg< x< 360deg: cos x= cos 2x

blsea [12.9K]

Answer:

$x=0^\circ,120^\circ,240^\circ,360^\circ$

Step-by-step explanation:

Use identities to set the equation up as a quadratic

$\cos x=\cos 2x;\:0^\circ \leq x \leq 360^\circ\\\\\cos x=2\cos^2 x-1\\\\0=2\cos^2 x-\cos x-1$

Make the substitution u=cos(x) and solve the quadratic

$0=2u^2-u-1\\\\0=(2u+1)(u-1)$

$\displaystyle 0=2u+1\\\\0=2\cos x+1\\\\-1=2\cos x\\\\-\frac{1}{2}=\cos x\\\\120^\circ,240^\circ=x$

$0=u-1\\\\0=\cos x-1\\\\1=\cos x\\\\0^\circ,360^\circ=x$

Hence, $x=0^\circ,120^\circ,240^\circ,360^\circ$

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1 year ago

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3 years ago

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Use substitution to solve the problem below algebraically. x = 41 x + 2y = 71

grandymaker [24]

Answer:

41 + 2y = 71

2y = 30

y = 15

Step-by-step explanation:

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